1. Field of the Invention
The disclosure relates to a vehicle door latch device with a power release mechanism, and in particular, it relates to a ratchet path disengagement mechanism provided in a ratchet release transmission path that transmits ratchet release operation force from the power release mechanism to a ratchet.
2. Description of the Related Art
There has been publicly known a convention vehicle door latch device as illustrated in FIG. 10 provided with a latch B that abuts on a striker A of a vehicle body when a vehicle door moves in a door-closing direction and rotates from an unlatch position to a latch position, a ratchet E that prevents a reversal of the latch B and holds the door in a door-closed state by engaging with a half latch step portion C and a full latch step portion D of the latch B, and a motor-type power release mechanism G coupled to the ratchet E through a ratchet release transmission path F, and in which door-opening is enabled by transmitting ratchet release operation force from the power release mechanism G to the ratchet E through the ratchet release transmission path F and by rotating the ratchet E against elasticity of a ratchet spring H such that it is released from the latch B. The vehicle door latch device provided with such power release mechanism G is frequently used in a sliding vehicle door.
In the above-described publicly known device, when a failure (motor failure, power supply failure, gear chipping, etc.) occurs to the power release mechanism G during operation, a power system of the power release mechanism G enters mechanical lock state, and the ratchet E, which is coupled to the power release mechanism G through the ratchet release transmission path F, also becomes inoperative accompanying the above-described mechanical lock state. The ratchet E becomes incapable of rotating in a direction to engage with the latch B, and door-closing may be incomplete. For this reason, a ratchet path disengagement mechanism J that switches from a “connected state” to a “disconnected state” is provided in the middle of the ratchet release transmission path F such that, when the ratchet E is bound at a releasing position due to the mechanical lock state of the power release mechanism G and becomes incapable of reengaging with the latch B, coupling between the power release mechanism G and the ratchet E is detached and that the ratchet E can be reengaged with the latch B by only the elasticity of the ratchet spring H even in a case where the power release mechanism G is in the mechanical lock state.
A ratchet path disengagement mechanism according to Japanese Patent Application Laid-open No. 2005-213818 is switched from the “connected state” to the “disconnected state” by a special method of using an existing component, whereby an end user is unable to deal with it.
A ratchet path disengagement mechanism according to Japanese Patent Application Laid-open No. 2014-074324 is switched from the “connected state” to the “disconnected state” by moving the door to close it, by rotating a latch in a latch direction by abutting it on a striker, and by interlockingly displacing an interlocking lever, whereby interlocking displacement force of the interlocking lever is transmitted to the ratchet path disengagement mechanism. In this configuration, it is necessary to add the interlocking lever that interlocks with rotation of the door-closing latch to a small door-closing latch unit (latch and ratchet mechanism). In many cases, a power close mechanism is connected to the door-closing latch, and adding of the interlocking lever may put a large burden on designing. In addition, since disengagement of the ratchet path disengagement mechanism is performed each time the door is closed, whereby operation noise thereof may also become a large problem.
A ratchet path disengagement mechanism according to Japanese Patent Application Laid-open No. 2014-152496 is switched from the “connected state” to the “disconnected state” by operating a specialized button provided on the door. Thus, although peculiarity of the ratchet path disengagement mechanism of Japanese Patent Application Laid-open No. 2005-213818 is avoided, existence of the button is not known to the end user, whereby it may not be a sufficient measure for emergency such as “the door does not close”.